Earth

(third solar system planet from the Sun)

Earth is the third solar system planet from the Sun
and the solar system's largest rocky planet. Its temperature
and atmospheric pressure are such that liquid water can exist
on the surface, which is mostly covered with water. Its atmospheric
makeup, with substantial oxygen, is influenced by life on the planet.
It is also geologically active, exhibiting plate tectonics.
Some characteristics:

Earth's single moon is notable for being nearer to Earth's size and mass
(1/4 the radius and 1% the mass) than the moons of the other planets
(excluding dwarf planetPluto and its largest moon, Charon).

As the only planet known to harbor life,
characteristics of Earth are considered when attempting to
discover potential
biosignatures, e.g., for the study of extra-solar planets.
Earth is plainly in the Sun's habitable zone, for which estimates
are refined over time as more information is available and considered.
Some recent determinations put Earth near the inner edge.

The term e­arth is also used for classes of exoplanets
that resemble the Earth, such as similar mass and/or constituents.